Japanese Unexamined Patent Application Publication No. 1-93182 (hereinafter referred to as “Patent Document 1”) describes a thermoelectric element in which n-type semiconductor members and p-type semiconductor members are connected in series and which, as a whole, has a large thermoelectromotive force. In this element, insulating layers and conductor layers are formed on opposite surfaces of adjacent n-type and p-type semiconductor plate members, and then the plate members are stacked. Consequently, the adjacent plate members are insulated from each other by the insulating layers at portions where connection is not required, and are electrically connected to each other by the conductor layers at portions where connection is required. Therefore, a complicated connection operation using lead wires is not required. Furthermore, the plate members are stacked after the insulating layers and the conductor layers are formed thereon by thick-film printing, and the insulating layers and the conductor layers join the plate members by firing. Consequently, the insulating layers and the conductor layers exhibit the function of joining the plate members in addition to the original functions of electrical insulation and connection. The thermoelectric element is composed of n-type semiconductor plate members and p-type semiconductor plate members and has a structure in which a plurality of plate members are stacked. Consequently, even if many n-type semiconductor members and p-type semiconductor members are combined, the entire element can be reduced in size or miniaturized, and its thermal capacity can be reduced so that temperature gradients can be sensitively detected.
Patent Document 1 discloses a case in which a Ba—Ti-based oxide is used as the n-type semiconductor, and a Ni—Mn—Cu-based oxide is used as the p-type semiconductor, and in its example, a p-type semiconductor prepared by adding CuO to NiMn2O4 is used.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 1-93182
However, the Seebeck coefficient of a Ni—Mn—Cu—O material, which is the p-type semiconductor in the example of Patent Document 1, is −160 μV/K at 20° C., and in order to use the material as a useful thermoelectric material, it is necessary to further increase the thermoelectromotive force.